Dishwasher tub gasket surface

ABSTRACT

A relatively smooth seating surface for a gasket for a dishwasher tub formed by an expanding process is made by displacing the material forming the seating surface sufficiently from its original position established by the expanding step that the wrinkles and irregularities formed during the expanding process are merged into the smooth surface.

United States Patent 1191 Long 1 1 Sept. 30, 1975 1 1 DISHWASHER TUBGASKET SURFACE [75] Inventor: Olan L. Long. Columbus. Ohio [73]Assignee: White-Westinghouse Corporation, Cleveland. Ohio 22 Filed: Dec.21. 1972 21 Appl. No.: 317.329

Related U.S. Application Data [62] Division of Ser. No. 141.685. May 10.1971. Pat. No.

[52] U.S. Cl 220/74; 49/485 [51] Int. Cl. B65D 7/42 [58] Field of Search220/74, 46 R; 134/58 DC,

134/200, 183; 113/120 M, 116 HA; 29/401. 402; 72/348; 49/485; 161/99,110

[56] References Cited UNITED STATES PATENTS 1.960.000 5/1934 Chesney113/120 M 1 979.-172 11/1934 Kelly 113/116 HA 2.235.386 3/1941 Rueckert134/200 2.274.835 3/1942 Koch 113/120 M 2.378.982 6/1945 Chesney...113/120 M 3.064.661 11/1962 Jacobs 134/181 3.229.061 1/1966 Han-off.v134/58 DL 3.268.144 8/1966 Gaunt 220/74 3.273.743 9/1966 McColl 20/46 R3.360.155 12/1967 Colonna 2 0/46 R 3.464.579 9/1969 Asenhauer "0/46 R3.603.035 9/1971 Kaldcnbcrg 49/485 FOREIGN PATENTS OR APPLICATIONS1.261.641 2/1968 Germany 134/200 Primary E.\'aminer-William 1. PriceAssistant Exmniner-Allan N. Shoap [57] ABSTRACT A relatively smoothseating surface for a gasket for a dishwasher tub formed by an expandingprocess is made by displacing the material forming the seating surfacesufficiently from its original position established by the expandingstep that the wrinkles and irregularities formed during the expandingprocess are merged into the smooth surface.

2 Claims, 4 Drawing Figures US. Patent Sept. 30,1975 3,908,854

DISHWASHER TUB GASKET SURFACE This is a division of application Ser. No.141,685, filed May l0, 1971, now U.S. Pat. No. 3,732,835, issued May 15,1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

The invention pertains to the art of dishwasher tubs and the method ofmaking them, and is specifically concerned with forming a smooth gasketseating surface on the tub.

2. Description of the Prior Art:

Applicant is unaware of prior art dishwasher patents consideredpertinent to this invention.

One known way of forming the generally right parallelepiped shape of adishwasher tub is to use the known expanding process in which segmenteddies disposed inside the tub form are moved outwardly to form thecontours in the tub walls. This process also accommodates forming agasket seating surface flange intended to be flat. However, it has beenmy experience that in using the expanding process to form dishwashertubs, irregularities and wrinkling of the material forming the gasketseating surface frequently occurs. In the past, efforts have been madeto flatten the surface fully by squeezing the wrinkles andirregularities out into the flat; however, even with this step it hasbeen my experience that the irregularities and wrinkles are notadequately removed to provide satisfactory seating in all cases.

This problem of irregularities in the material occasioned by use of theexpanding process is known generally in the metal working art, asevidenced, for example, in "Metals Handbook 8th Edition, Volume 4, ofthe American Society for Metals, wherein it is stated on page 86 thatThe presence of gaps between the forming segments is one of thedrawbacks of this method and is the reason that an alternative method,such as rubber pad forming, is sometimes selected.

SUMMARY OF THE INVENTION In accordance with my invention, a relativelysmooth seating surface for a gasket on a dishwasher tub is provided bydisplacing the material fonning that surface sufficiently from itsoriginal position established by the expanding step that the wrinklesand irregularities, to the extent they exist, are merged into the smoothsurface in its displaced position. This is in contrast to the notedrestriking step in the prior art in which the surface is restruck in aneffort to flatten the surface to squeeze out any irregularities therein.The displacement contemplated in accordance with the invention resultsin a stretching of the material wherein the final contour of the seatingsurface is concave.

DRAWING DESCRIPTION FIG. 1 is a partly broken, schematic, side view ofan expanding process arrangement by which the dishwasher tub isinitially formed to its general shape;

FIG. 2 is a perspective view of the dishwasher tub as finally formed;

FIG. 3 is a perspective view ofa fragment of the border of the openfront face of the dishwasher tub for the purpose of illustrating insomewhat exaggerated form a character of wrinkles and irregularitieswhich may be formed in the seating surface during the expanding process;and

FIG. 4 is a horizontal section corresponding to the line IVIV of FIG. 2and illustrating in somewhat exaggerated form the displaced position ofthe seating surface.

DESCRIPTION OF THE PREFERRED EMBODIMENT The dishwasher tub has agenerally right parallelepiped shape as formed and shown in FIG. 2 andincludes a top wall 10, bottom wall 12, opposite side walls 14 and 16,and rear wall 18, the center portion 20 of which is absent during theexpanding process and is subsequently welded to the remainder of therear wall. The tub also includes an open front space 22 defined by theperimetric border portion generally designated 24. During the expandingprocess the various embossments, ribs, and the perimetric border portionare also formed, with the exception that the rearwardly directed stubflange 26 along the outer edge of the perimetric border portion occupiesthe same plane as the front flange 28. v

While expanding processes are well known, a schematic illustration ofthe arrangement for forming a dishwasher tub is shown in FIG. 1 in whichthe female die or backup is indicated by the numeral 30, the segmentedmale dies by the numeral 32, and the ram or punch press by the numeral34. It will be appreciated that FIG. 1 is a simplified schematic anddoes not show the intricate configurations in the dies to accomplishforming the embossments and the perimetric border portion 24.

During the expanding process illustrated in FIG. 1 the segmented diearrangement occasions the creation of wrinkles and irregularities of arelatively minor nature in different parts of the tub. In most areas thewrinkles and irregularities, because of their minor nature, areinsufficient to create any problem and in fact are generally soimperceptible that the tub must be examined relatively closely to detectthese irregularities. However, it has been found that as to the seatingsurface to which a gasket is either attached, or against which it seatsfor sealing purposes, minor irregularities and wrinkles can andfrequently do permit leakage of water at such locations. In FIG. 3, afragment of the perimetric border 24 is illustrated in which wrinkles 36and irregularities 38 are shown in exaggerated size on the gasketseating surface 40 of the perimetric border portion. It is here notedthat while in the illustrated embodiment the gasket is carried by thedoor (not shown) of the dishwasher, the problem of irregularitiespermitting leakage has been found to exist irrespective of whether thesurface with the irregularities is that to which the gasket is attached,or is that to which the gasket moves against and seats to effect a seal.

In accordance with the invention, the material forming the seatingsurface 40 is restruck in a press forming operation to displacesubstantially all of the material forming the seating surfacesufficiently from its original position, as established by the expandingstep, that the wrinkles and irregularities are merged into a smoothcontoured surface. As seen in FIG. 4, the dash line 42 indicates theoriginal flat plane which the forward surface of the seating surface 40occupied after the expanding step, with the restriking operationcontouring the surface into the concave shape, as viewed from the frontof the tub, this concave shape being shown in slightly exaggerated formin FIG. 4. In practice, as

found with the segmented dies used and in which the width of the seatingsurface 40 is about 0.56 a contoured depth of 0.020 inches plus or minus0.010 is suf ficient to merge the wrinkles and irregularities into asmooth seating surface. It will be appreciated that a materialdisplacing step need not result in a concave form if the originalcontour is convex instead of flat. and the restriking changes thecontour from greater convexity to less convexity. However, the concavefinal contour is the currently preferred arrangement.

The restriking of the seating surface 40 to provide the contour may beaccomplished in connection with the press forming step during which theflange 28 is provided at the edge of the front flange 26.

I claim as my invention:

l. A metal dishwasher tub formed to include a plurality of walls and aforwardly open face defined by perimetric border portions including aseating surface for a gasket. said seating surface extending along atleast some of the sides of said open face. said seating surface having aconcave shape in transverse section, said concave shape being formed byrestriking said seating surface to effect sufficient displacement of thematerial forming said seating surface to eliminate irregularitiescreated in said seating surface during a tub-forming expanding process.

2. A dishwasher tub according to claim 1 wherein:

said concave shape is presented as viewed from for wardly of said tub.

1. A metal dishwasher tub formed to include a plurality of walls and aforwardly open face defined by perimetric border portions including aseating surface for a gasket, said seating surface extending along atleast some of the sides of said open face, said seating surface having aconcave shape in transverse section, said concave shape being formed byrestriking said seating surface to effect sufficient displacement of thematerial forming said seating surface to eliminate irregularitiescreated in said seating surface during a tub-forming expanding process.2. A dishwasher tub according to claim 1 wherein: said concave shape ispresented as viewed from forwardly of said tub.